1 /* POSIX spinlock implementation. Arm version.
2 Copyright (C) 2000 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public License as
7 published by the Free Software Foundation; either version 2.1 of the
8 License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; see the file COPYING.LIB. If not,
17 write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
18 Boston, MA 02111-1307, USA. */
19
20 #include <errno.h>
21 #include <pthread.h>
22 #include "internals.h"
23
24
25 int
__pthread_spin_lock(pthread_spinlock_t * lock)26 __pthread_spin_lock (pthread_spinlock_t *lock)
27 {
28 unsigned int val;
29
30 do
31 __asm__ __volatile__ ("swp %0, %1, [%2]"
32 : "=r" (val)
33 : "0" (1), "r" (lock)
34 : "memory");
35 while (val != 0);
36
37 return 0;
38 }
weak_alias(__pthread_spin_lock,pthread_spin_lock)39 weak_alias (__pthread_spin_lock, pthread_spin_lock)
40
41
42 int
43 __pthread_spin_trylock (pthread_spinlock_t *lock)
44 {
45 unsigned int val;
46
47 __asm__ __volatile__ ("swp %0, %1, [%2]"
48 : "=r" (val)
49 : "0" (1), "r" (lock)
50 : "memory");
51
52 return val ? EBUSY : 0;
53 }
weak_alias(__pthread_spin_trylock,pthread_spin_trylock)54 weak_alias (__pthread_spin_trylock, pthread_spin_trylock)
55
56
57 int
58 __pthread_spin_unlock (pthread_spinlock_t *lock)
59 {
60 return *lock = 0;
61 }
weak_alias(__pthread_spin_unlock,pthread_spin_unlock)62 weak_alias (__pthread_spin_unlock, pthread_spin_unlock)
63
64
65 int
66 __pthread_spin_init (pthread_spinlock_t *lock, int pshared)
67 {
68 /* We can ignore the `pshared' parameter. Since we are busy-waiting
69 all processes which can access the memory location `lock' points
70 to can use the spinlock. */
71 return *lock = 0;
72 }
weak_alias(__pthread_spin_init,pthread_spin_init)73 weak_alias (__pthread_spin_init, pthread_spin_init)
74
75
76 int
77 __pthread_spin_destroy (pthread_spinlock_t *lock)
78 {
79 /* Nothing to do. */
80 return 0;
81 }
82 weak_alias (__pthread_spin_destroy, pthread_spin_destroy)
83